Blackstar HT100 repair

Blackstar HT100 repair

This Blackstar HT100 repair was completed for the co owner of an exciting new Grantham based venture ‘Melody Music Rooms’ in Grantham.

Melody music rooms are a rehearsal space, recording facility and teaching space located on Westgate in Grantham . It’s the brainchild of a group of Lincolnshire and Nottinghamshire music teachers who wanted to provide better music services in the area. Not just a building, they run jam nights and busking sessions featuring local young (and old!) musicians. It’s great to have these guys raising the profile of live music in the area, so do check them out on

I’m told that this amp has played Wembley(!) as the owners of Melody Music played some high profile support gigs with their old band. It had been retired when it started blowing fuses, but the owner wanted it brought back to life for the new Melody venture.

There were a couple of valves to replace and the amp had blown the bridge rectifer diodes. Unfortunately Blackstar don’t provide schematics for their amps so it’s always a bit of a tough job repairing Blackstar gear.

Normally at this point I’d put a clip of my repair video, but here’s the repaired amp being used in the studio at Melody Music Rooms.

If you need a Blackstar HT100 repair, please drop me a line.

Blackstar Series One repair S1-104EL34

Blackstar Series One repair

This Blackstar Series One repair from February was a bit of a mess! The amp had unfortunately received the unhelpful care of another repairer who had left the amp in a terrible state. If you don’t like to see damaged PCBs, look away now.

It was brought to me because it was blowing fuses at gigging levels. The owner had bought it second hand and it had started blowing fuses recently. A quick fix was managed in time for a gig!

I’m not sure what the original fault was with this amp, but whoever had previously attempted to fix it was very much of the ‘add more solder’ school of repairing! I suspect that they had not attempted to remove the board and had just tried to repair the amp from the top side only in doing so they’d damaged to PCB and left the transistor hanging by a thread of pad..

Blackstar Series One repair3You can see the horrible original work on the left and my improved fix on the right of the image. I removed the board and cut away the damaged track and recreated a solid connection with solid core wire on the board reverse. I replaced the burnt out components nearby with suitably rated high power resistors. I also replaced the transistor.

The whole job took 3 hours and included a valve test (revealing three worn preamp valves) and an additional (FOC) 1 hour soak test at gigging levels.

If you have a blackstar series one repair, please drop me a line.

Here’s a video of the amp, once fixed.

Blackstar ID30 TVP repair

Blackstar ID-30 TVP repair

This is the first Blackstar ID30 TVP repair that I’ve come across, but there wasn’t much to the job. The owner had lent  his amp to a friend and the tip of the jack socket had fallen off inside the amp.

I was really impressed with the build quality on this amp and it was very easy to work on. It was a very quick job to remove the separate input jack PCB, desolder the socket, remove the offending jack tip, resolder the socket, refit the board and reassemble the unit. This all fell within my minimum diagnostic charge.

I was very impressed by the transparency of the inbuilt noise suppressor on the Blackstar ID:30 TVP OD2 channel. This thing has an insane amount of gain and is totally silent, but sustain isn’t really affected. I guess that they sense the input right at the front end of the amp, but do the suppression just before the power amp. Like a 4 cable ISP Decimator, but free! Great stuff.

I’d have liked to have taken a look at the TVP on an oscilloscope, to see what the guys are doing here but I didn’t get the chance. My completely unjustified guess is that it’s changing the power amp output impedance along similar lines to the patent that Bruce Keir filed when he was with Marshall. But that’s just a guess.

If you need a Blackstar ID30 TVP repair, please get in touch.

Blackstar HT5 Repair, Keld Ampworks, Newark, near Stamford

Blackstar HT-5 repair

I’ll admit this Blackstar HT5 repair had me confused for a bit. It was brought to me from Stamford Endowed School, which isn’t that far away from my workshop in Newark, it is just down the A1.

The amp arrived with no sound output from the speakers. The valves tested fine, one 12ax7 and one 12bh7.

Looking inside the amp I could see signal on both grids of the 12ax7, but nothing was getting through to the output stage.

Using a thermocouple I tested the temperature of the semiconductors in the amp and found that the two MOSFETs were getting rather hot!

Upon inspection, I saw that somebody had drilled two little holes between the MOSFET legs and left all the swarf (mangled metal pad and PCB resin).

It turns out that there’s a forum post saying that the MOSFET pads were apparently quite close together and prone to arcing. I think that somebody read that post and decided to go DIY on this amp, not understanding that leaving chewed up pad around the holes would gonna cause a worse problem than arcing. 🙁 It probably worked for a bit but it worketh no longer.

After replacing the burnt out drain resistors and the damaged FETs, the amp was back up and running. These are really great little amps and put out a lot of volume, despite their 5W rating.

If you need a Blackstar HT5 repair, please contact me.

Blackstar amp Repair – Series 1-45

Blackstar amp repair

This Blackstar repair was a simple valve amp service before the amplifier was sold. The amp is a series 1-45 2×12 combo. It’s a fantastic 2 channel amp with 4 modes, bright Clean, warm clean, Crunch and Super Crunch.

The amplifier uses Blackstar’s DPR and ISF patents, you can read more about Blackstar’s DPR on my valve amp attenuators page.

The amplifier was performing well, but a test on the valve tester turned up two faulty preamp valves which were replaced. The week before, I’d had another Blackstar amp repair, but as they’re a fairly new brand, I don’t get many Blackstar repairs!

Blackstar amps are one of the many types that I repair, please get in touch if you need my help.

Blackstar Repair – HT40


Recently, a Blackstar amp repair was brought to my workshop in Newark. The amp was an HT40 (the Club 40 combo) in working condition, but the owner wanted to try a new set of EL34 power valves in the amp. He selected a matched pair of Tung Sol with slightly higher gain (according to my valve tester) than then outgoing stock Ruby parts.

However, whilst checking the amp over my valve tester highlighted a fault in one of the Sovtek preamp valves, so I’ve replaced this with a JJ ECC83S.


There’s an interesting and fairly unusual element in these Blackstar HT amps – they appear to use a transistor Phase inverter (you can see it in the image at the top), so all the 4 gain stages in the 2 12AX7 preamps are used purely for gain in the preamp circuit. They sound great. This unit doesn’t use the DPR circuit that I mention on that page.

Anyone who knows me as a player, rather than a tech will know I’m a bit of a Blackstar amp fan. I play a Blackstar Series 1 50W head (recently upgraded from a heavy Blackstar Series 1 45 combo). I almost bought one of the these HT40s actually!blackstar-valve-amp-bias

If you have a blackstar repair, please get in touch!